Try to breakup some import cycles dependencies.

ipython · Carreau · Nov 7, 2025 · Nov 7, 2025 · Dec 3, 2025 · Feb 20, 2026
commit 739be9e1654680d378675ef9992277e03a7156c0
diff --git a/IPython/core/debugger.py b/IPython/core/debugger.py
@@ -132,7 +132,6 @@
 from contextlib import contextmanager
 from functools import lru_cache
 
-from IPython import get_ipython
 from IPython.core.debugger_backport import PdbClosureBackport
 from IPython.utils import PyColorize
 from IPython.utils.PyColorize import TokenStream
@@ -243,6 +242,8 @@ def __init__(
         stdin=None,
         stdout=None,
         context: int | None | str = 5,
+        *,
+        shell: TerminalInteractiveShell = None,
         **kwargs,
     ):
         """Create a new IPython debugger.
@@ -258,6 +259,7 @@ def __init__(
         context : int
             Number of lines of source code context to show when
             displaying stacktrace information.
+        shell : InteractiveShell
         **kwargs
             Passed to pdb.Pdb.
 
@@ -283,16 +285,6 @@ def __init__(
         # IPython changes...
         self.shell = get_ipython()
 
-        if self.shell is None:
-            save_main = sys.modules["__main__"]
-            # No IPython instance running, we must create one
-            from IPython.terminal.interactiveshell import TerminalInteractiveShell
-
-            self.shell = TerminalInteractiveShell.instance()
-            # needed by any code which calls __import__("__main__") after
-            # the debugger was entered. See also #9941.
-            sys.modules["__main__"] = save_main
-
         self.aliases = {}
 
         theme_name = self.shell.colors

diff --git a/IPython/core/display.py b/IPython/core/display.py
@@ -17,6 +17,7 @@
 
 from typing import Optional
 
+from IPython.core.pylabtools import _pngxy
 from IPython.testing.skipdoctest import skip_doctest
 from . import display_functions
 
@@ -799,13 +800,6 @@ def _repr_javascript_(self):
 _WEBP = b"WEBP"
 
 
-def _pngxy(data):
-    """read the (width, height) from a PNG header"""
-    ihdr = data.index(b'IHDR')
-    # next 8 bytes are width/height
-    return struct.unpack('>ii', data[ihdr+4:ihdr+12])
-
-
 def _jpegxy(data):
     """read the (width, height) from a JPEG header"""
     # adapted from http://www.64lines.com/jpeg-width-height

diff --git a/IPython/core/interactiveshell.py b/IPython/core/interactiveshell.py
@@ -71,7 +71,6 @@
 from IPython.core.displayhook import DisplayHook
 from IPython.core.displaypub import DisplayPublisher
 from IPython.core.error import InputRejected, UsageError
-from IPython.core.events import EventManager, available_events
 from IPython.core.extensions import ExtensionManager
 from IPython.core.formatters import DisplayFormatter
 from IPython.core.history import HistoryManager, HistoryOutput
@@ -83,7 +82,7 @@
 from IPython.core.profiledir import ProfileDir
 from IPython.core.tips import pick_tip
 from IPython.core.usage import default_banner
-from IPython.display import display
+from IPython.core.display_functions import display
 from IPython.paths import get_ipython_dir
 from IPython.testing.skipdoctest import skip_doctest
 from IPython.utils import PyColorize, io, openpy, py3compat
@@ -1103,6 +1102,8 @@ def set_hook(self, name, hook, priority=50, str_key=None, re_key=None):
     #-------------------------------------------------------------------------
 
     def init_events(self):
+        # Import here to break circular dependency with IPython.core.events
+        from IPython.core.events import EventManager, available_events
         self.events = EventManager(self, available_events)
 
         self.events.register("pre_execute", self._clear_warning_registry)

diff --git a/IPython/core/profiledir.py b/IPython/core/profiledir.py
@@ -1,4 +1,3 @@
-# encoding: utf-8
 """An object for managing IPython profile directories."""
 
 # Copyright (c) IPython Development Team.
@@ -7,10 +6,10 @@
 import os
 import shutil
 import errno
+import IPython
 from pathlib import Path
 
 from traitlets.config.configurable import LoggingConfigurable
-from ..paths import get_ipython_package_dir
 from ..utils.path import expand_path, ensure_dir_exists
 from traitlets import Unicode, Bool, observe
 
@@ -242,3 +241,10 @@ def find_profile_dir(cls, profile_dir, config=None):
         if not os.path.isdir(profile_dir):
             raise ProfileDirError('Profile directory not found: %s' % profile_dir)
         return cls(location=profile_dir, config=config)
+
+
+def get_ipython_package_dir() -> str:
+    """Get the base directory where IPython itself is installed."""
+    ipdir = os.path.dirname(IPython.__file__)
+    assert isinstance(ipdir, str)
+    return ipdir
diff --git a/IPython/core/pylabtools.py b/IPython/core/pylabtools.py
@@ -7,12 +7,19 @@
 from io import BytesIO
 from binascii import b2a_base64
 from functools import partial
+import struct
 import warnings
 
-from IPython.core.display import _pngxy
 from IPython.utils.decorators import flag_calls
 
 
+def _pngxy(data):
+    """read the (width, height) from a PNG header"""
+    ihdr = data.index(b'IHDR')
+    # next 8 bytes are width/height
+    return struct.unpack('>ii', data[ihdr+4:ihdr+12])
+
+
 # Matplotlib backend resolution functionality moved from IPython to Matplotlib
 # in IPython 8.24 and Matplotlib 3.9.0. Need to keep `backends` and `backend2gui`
 # here for earlier Matplotlib and for external backend libraries such as
@@ -441,7 +448,7 @@ def import_pylab(user_ns, import_all=True):
 
     # IPython symbols to add
     user_ns['figsize'] = figsize
-    from IPython.display import display
+    from IPython.core.display_functions import display
     # Add display and getfigs to the user's namespace
     user_ns['display'] = display
     user_ns['getfigs'] = getfigs

diff --git a/IPython/paths.py b/IPython/paths.py
@@ -5,6 +5,7 @@
 from warnings import warn
 
 import IPython
+from IPython.core.profiledir import ProfileDir, ProfileDirError, get_ipython_package_dir
 from IPython.utils.importstring import import_item
 from IPython.utils.path import (
     get_home_dir,
@@ -86,11 +87,6 @@ def get_ipython_cache_dir() -> str:
     return ipdir
 
 
-def get_ipython_package_dir() -> str:
-    """Get the base directory where IPython itself is installed."""
-    ipdir = os.path.dirname(IPython.__file__)
-    assert isinstance(ipdir, str)
-    return ipdir
 
 
 def get_ipython_module_path(module_str):
@@ -113,7 +109,6 @@ def locate_profile(profile='default'):
 
     I.e. find $IPYTHONDIR/profile_whatever.
     """
-    from IPython.core.profiledir import ProfileDir, ProfileDirError
     try:
         pd = ProfileDir.find_profile_dir_by_name(get_ipython_dir(), profile)
     except ProfileDirError as e:

diff --git a/IPython/terminal/debugger.py b/IPython/terminal/debugger.py
@@ -2,8 +2,10 @@
 import os
 import sys
 
+from IPython import get_ipython
 from IPython.core.debugger import Pdb
 from IPython.core.completer import IPCompleter
+from IPython.terminal.interactiveshell import TerminalInteractiveShell
 from .ptutils import IPythonPTCompleter
 from .shortcuts import create_ipython_shortcuts
 from . import embed
@@ -26,7 +28,16 @@ class TerminalPdb(Pdb):
     """Standalone IPython debugger."""
 
     def __init__(self, *args, pt_session_options=None, **kwargs):
-        Pdb.__init__(self, *args, **kwargs)
+        shell = get_ipython()
+        if shell is None:
+            save_main = sys.modules["__main__"]
+            # No IPython instance running, we must create one
+            shell = TerminalInteractiveShell.instance()
+            # needed by any code which calls __import__("__main__") after
+            # the debugger was entered. See also #9941.
+            sys.modules["__main__"] = save_main
+
+        Pdb.__init__(self, *args, shell=shell, **kwargs)
         self._ptcomp = None
         self.pt_init(pt_session_options)
         self.thread_executor = ThreadPoolExecutor(1)

diff --git a/IPython/terminal/interactiveshell.py b/IPython/terminal/interactiveshell.py
@@ -46,7 +46,6 @@
 from pygments.styles import get_style_by_name
 from pygments.style import Style
 
-from .debugger import TerminalPdb, Pdb
 from .magics import TerminalMagics
 from .pt_inputhooks import get_inputhook_name_and_func
 from .prompts import Prompts, ClassicPrompts, RichPromptDisplayHook
@@ -246,6 +245,7 @@ class TerminalInteractiveShell(InteractiveShell):
 
     @property
     def debugger_cls(self):
+        from .debugger import TerminalPdb, Pdb
         return Pdb if self.simple_prompt else TerminalPdb
 
     confirm_exit = Bool(True,

diff --git a/IPython/utils/io.py b/IPython/utils/io.py
@@ -15,10 +15,6 @@
 from pathlib import Path
 from warnings import warn
 
-from IPython.utils.decorators import undoc
-from .capture import CapturedIO, capture_output
-
-
 class Tee:
     """A class to duplicate an output stream to stdout/err.